Preparation and structure of AlW thin films

Thin films of AlW alloys were prepared by co-deposition of pure aluminum and pure tungsten, each sputtered by an independently controlled magnetron source. The deposition rate at the substrate (glass, fused quartz, and alumina ceramic), positioned 5 cm away from the target surface was 0.1-0.2 nm/s for pure metals, and the final film thickness was a few mu m Completely amorphous films were obtained in the Al80W20-Al67W33 composition range. At higher tungsten content, the W(AI) solid solution and pure tungsten phases appeared. The amorphous alloys exhibit a high negative temperature coefficient of the electric resistivity, increasing with the aluminum content up to -5.5 10(-4) K-l. Finally, the amorphous AIW alloys exhibit a remarkable microhardness (6-7 GPa), and are structurally stable up to at least 400 degrees C. (C) 1998 Elsevier Science S.A.